1. Field of the Invention
The present invention relates to a cabin lamp and more particularly to a cabin lamp that has a longer useful life, generates less heat and is suitable as a reading lamp for airplanes and automobiles.
2. Prior Art
FIG. 5 shows one example of a conventional cabin lamp. The cabin lamp 1 is, for example, a reading lamp for an airplane.
The cabin lamp 1 is supported by a panel 2 so as to be rotatable in a predetermined angle range about its axis.
A lamp housing 3 of the cabin lamp 1 has a spherical external side surface and is rotatably supported by the panel 2. A reflector 4 is installed in the lamp housing 3. A lamp socket 5 is detachably mounted to the rear end portion of the lamp housing 3, and an incandescent bulb 6 is detachably mounted to the lamp socket 5.
The incandescent bulb 6 is of a type in which a cylindrical cap 9 is mounted to one end of a glass bulb 8 having a filament 7 sealed therein. Connector pins 11 (only one pin is shown in FIG. 5) protrude from the side surface of a cylindrical element 10 of the cap 9 made of conductive metal, and a feeder terminal 12 insulated with respect to the cylindrical element is disposed at one end of the cylindrical element 10.
A cylindrical holder 13 made of conductive metal is disposed inside the lamp socket 5, and the so-called J-shaped slots 14 (only one slot is shown) are formed in the holder 13. Further, a flexible feeder contact 15 is disposed on the lamp socket 5. The feeder contact 15 is connected to the power source through a switch 16 provided in the panel 2. The holder 13 is grounded.
The connector pins 11 of the cap 9 of the incandescent bulb 6 are guided along the J-shaped slots 14 of the holder 13 of the lamp socket 5 and received in the holder 13; and when the connector pins 11 are rotated along the bent portions of the J-shaped slots 14, the feeder contact 15 of the lamp socket 5 elastically contacts the feeder terminal 12, causing the connector pins 11 to be supported by the bent portions of the J-shaped slots 14. The incandescent bulb 6 is thus held in the lamp socket 5.
Furthermore, an annular bezel 17 is detachably fitted to the front end of the lamp housing 3 of the cabin lamp 1. A lens 19 having minute fisheye steps 18 formed on its inner surface is fitted to the bezel 17.
In the structure above, when the switch 16 is switched to the ON side, the feeder terminal 12 of the incandescent bulb 6 is connected to the power source through the switch 16 and the feeder contact 15 of the lamp socket 5. Further, since the cylindrical element 10 of the cap 9 is grounded through the connector pins 11 and the holder 13 of the lamp socket 5, electricity is supplied to the filament 7 and the lamp is lit.
In the above-described cabin lamp 1, the light source is an incandescent bulb and the internal volume is small. Accordingly, temperatures of the lamp housing 3 and bezel 17 tend to become high. This would raise the cabin temperature or give a user a burn when he/she touches the bezel 17 for adjustment of the illumination position.
Also, the life of incandescent bulbs is relatively short; and as a result, it is necessary to replace the incandescent bulb 6 frequently.
FIG. 6 shows a cabin lamp 20 that uses a light emitting diode (LED) as the light source. This type of lamp is proposed for the purpose of solving the problem that occurs when incandescent bulbs are used as the light source as described above.
The cabin lamp 20 is also for a reading lamp of an airplane, and it is supported by a panel (not shown) so as to be rotatable in a predetermined angle range.
A printed circuit board 23 with a plurality of LEDs 22 mounted thereon is installed in a lamp housing 21 that is rotatably supported by the panel. A heat sink 24 is also installed in the lamp housing 21. The heat sink 24 is installed on the backside of the printed circuit board 23. A heat radiation rubber 25 is laminated on the surface of the heat sink 24 that faces the printed circuit board 23.
An annular bezel 26 is detachably mounted to the front end of the lamp housing 21. A lens 28 having minute fisheye steps 27 formed on the inner surface thereof is fitted to the bezel 26.
In the above cabin lamp 20, generated heat is small because the light source is the LED 22. Accordingly, the problem of temperature inside the cabin becoming high or the problem of a user getting burn is solved. Further, since the life of LEDs is longer than incandescent bulbs, there is an advantage to use LEDs that the light source does not need to be replaced frequently.
However, with the above-described cabin lamp 20, since the printed circuit board 23 having the LEDs 22 thereon is fitted to the lamp housing 21, the entire lamp including the lamp housing 21 needs to be replaced when a cabin lamp having an incandescent bulb as the light source is to be replaced with a cabin lamp having the LEDs 22 as the light source. This presents a cost problem.
Further, the new cabin lamp 20 with LEDs must be installed in the panel 2 after the old cabin lamp 1 with an incandescent bulb is removed from the panel 2. The problem is that the replacement work takes time and man power.
Therefore, it is an object of the present invention to provide a new cabin lamp that has a longer useful life and generates a small amount of heat by using an LED as the light source.
It is another object of the present invention to provide a cabin lamp that has a good interchangeability with a cabin lamp that has an incandescent bulb as the light source.
The above objects are accomplished by a unique structure for a cabin lamp of the present invention, wherein an LED module, in which a printed circuit board on which a plurality of LEDs are disposed and a plurality of reflectors that surround the LEDs separately so as to reflect the light from the LED substantially forward are mounted to a frame-shaped bezel, is detachably attached to a front end portion of a lamp housing, and wherein the LED module is connected through a connector to a feeder element provided in the lamp housing.
The thus structured cabin lamp of the invention has a longer useful life and small heat generation because the LED is used as the light source.
Further, in the present invention, the light source portion is modularized. Accordingly, when changing the light source from the incandescent bulb to LED, only the bezel of the cabin lamp having the incandescent bulb needs to be removed, and then the LED module is instead installed. Accordingly, the replacement can be done easily and quickly.